​Technical Session 11: Brewhouse Operations Session

ABSTRACT: The nitrogen compounds in mash contribute not only to beer taste, but also to the brewing process, nitrogen source for yeast, and beer filterability. For this reason, control of protein modification in malting and mashing is very important, and we must consider optimizing mashing procedures depending on malt quality and vice versa. Because it is both easy and economical, it has become popular to use malts with relatively high protein modification. However, this may cause low fullness or an unpleasant aftertaste if the mashing method is not carefully considered. I reported at MBAA in 2010 that relatively low protein-modified malt and low mashing-in temperature led to better fullness and a bitter quality. Decoction beer has better fullness and bitter quality than infusion beer when relatively low protein-modified malt and a high mashing-in temperature were used. In order to improve the quality of decoction beer further, the influence of the mashing-in temperature and the heating process in the kettle mash was investigated using laboratory scale mashing apparatus (50 g of malt). Because it is also known that the protease activity of low-modified malt is improved by a low mashing-in temperature of 35°C, we first investigated the effect of mashing-in temperature in the kettle mash on extraction and degradation of nitrogen compounds. A low mashing-in temperature of 35°C produced more nitrogen compounds in the mash than a temperature of 45°C. The appropriate heating rate and rest temperature of the kettle mash produced larger quantities of nitrogen compounds than were produced without a rest process in the same length of time. We have described the suitable single decoction mashing procedure for better extraction and degradation of nitrogen compounds as determined by laboratory scale mashing experiments, and its influence on beer quality was evaluated on a 100-L pilot brew scale.

Taichi Maruhashi graduated with an M.S. degree from the Tokyo University of Science in 2001. After joining Suntory, he worked for six years in the position of second brewmaster at the Suntory Tonegawa brewery in Gumma, Japan. He then went to Technische Universität München, Weihenstephan, in Germany as an international student and studied there for three years. He currently works in beer development.